Buying Firewood Guide
Firewood logs are sold by volume rather than by weight. This is because the wetter the wood, the heavier it is, but the lower the calorific value. You need to have a high calorific value consistent with reasonable cost, so you need dry wood, which is therefore light in weight.
Volume
Logs are typically sold by volume, which is usually stated in cubic meters (m) or liters. Volume can be affected by whether the logs are "loose filled" or "close stacked". Close stacked logs have more logs per cubic meter than loose filled logs.
Weight
Wet logs weigh more than dry logs, so a load of seasoned logs will weigh less than a load of wet logs.
Moisture content
Logs can be categorized by their moisture content, which can affect their calorific value. Kiln-dried logs have less than 20% moisture content, seasoned logs have 25–50% moisture content, and unseasoned logs have over 50% moisture content. Kiln-dried logs produce twice as much heat as seasoned logs of the same volume.
Density
The density of the wood affects its weight. Hardwoods, like oak or ash, are denser and weigh more than softwoods, like pine or spruce. The average density of UK hardwoods is 700 kg per solid cubic meter, while the average density of softwoods is 500 kg per solid cubic meter.
